Several years ago, I picked up a small lot of Iranian stamps from a dealer while attending the StampShow
2016 in NYC where we had a booth. I suspected there may be varieties in this lot, so I purchased the lot
of 22 stamps for $7 and just got around to identifying the stamps now.

Today I will show you how to identify the 1911-1921 stamps of Persia or Iran as it is known today.  There are 21 stamps in the series, but there are 2 major types & 4 different perf variations resulting in over 120 possibilities ranging in value from 25c to over $3000.

The first & easiest way to identify this series is by the two types. They are known as the Tall & short portrait versions. These 2 types are a result of the printing method used: Wet print vs dry print. The wet print varieties tended to shrink after they dried and hence resulted in a shorter vignette which is the central engraved area depicting Ahmad Shah Qajar. These two varieties can be easily differentiated by measuring the height of the central vignette.

You can use EzImage or EzPerf to easily measure this for you as shown below. Using EzImage, Select the measure tool, then set the units to mm and Draw a line as shown from the TOP of the border line of the Vignette to the BOTTOM of the border line of the Vignette as shown ( you want the distance between the BLUE Arrows).
Using EzPerf is also shown here below

Using EzImage

Using EzPerf

Here are the steps you can take to measure your stamps
First you scan the stamps using EzImage on the pages that they came on at 300 dpi & load the images into EzPerf and use the Auto-separate feature to Measure the perforations & then the height of the vignette.

The perf varieties greatly affect the values, so it pays to measure carefully. In this batch of stamps I found over $150 worth of varieties. Not bad for a $7 purchase.
You can do the same with the use of the right tools in your philatelic toolkit. If EzPerf and EzImage are not in your toolkit, they should be!

Watch this short video of EzPerf being used to measure the varieties  How to Identify the 1911 stamps of Iran